This invention relates generally to apparatus for filling a container with dry particulate material, and more particularly concerns a filling apparatus having a clean shutoff conveyor for preventing undesirable dribble after filling a container with particulate materials such as toner.
Currently when filling particulate materials, for example toners into toner containers, toner is transported from the toner supply hopper into the container by a rotating auger. The auger is a spiral shaped mechanical part which pushes particles of toner inside a fill tube by direct mechanical contact. The nature of this mechanical contact process creates substantial limitations on accuracy and productivity of the toner filling operation. The speed of the toner movement in the fill tube is proportional to the speed of rotation of the auger and is limited by heat release due to auger/toner/funnel friction.
Toner containers for small low cost printers and copiers typically have a small opening into which the toner is to be added. Furthermore, the toner containers often have irregular shapes to conform to the allotted space within the copying machine. Therefore it becomes difficult to fill the toner container because of the small tube required to fit into the small toner container opening and secondly for all the toner within the container to completely and evenly fill the remote portions of the container before the container overflows.
Some of the problems associated with controlling the filling of such toner containers are due primarily to the properties of the toner. Toner is the image-forming material in a developer which when deposited by the field of an electrostatic charge becomes the visible record. There are two different types of developing systems known as one-component and two-component systems.
In one-component developing systems, the developer material is toner made of particles of magnetic material, usually iron, embedded in a black plastic resin. The iron enables the toner to be magnetically charged. In two-component systems, the developer material is comprised of toner which consists of small polymer or resin particles and a color agent, and carrier is which consists of roughly spherical particles or beads usually made of steel. An electrostatic charge between the toner and the carrier bead causes the toner to cling to the carrier in the development process. Control of the flow of these small, abrasive and easily charged particles is very difficult.
The one-component and two-component systems utilize toner that is very difficult to flow. This is particularly true of the toner used in two component systems, but also for toner for single component systems. The toner tends to cake and bridge within the hopper. This limits the flow of toner through the small tubes which are required for addition of the toner through the opening of the toner container. Also, this tendency to cake and bridge may cause air gaps to form in the container resulting in partial filling of the container.
Attempts to improve the flow of toner have also included the use of an external vibrating device to loosen the toner within the hopper. These vibrators are energy intensive, costly and not entirely effective and consistent. Furthermore, they tend to cause the toner to cloud causing dirt to accumulate around the filling operation.
Other attempts made to effectively fill such toner containers have included use of adapters positioned on the end of the toner filling auger which has an inlet corresponding to the size of the auger and an outlet corresponding to the opening in the toner container. Clogging of the toner, particularly when attempting to increase toner flow rates and when utilizing toners with smaller particle size, for example, color toners having a particle size of 7 microns or less, has been found to be a perplexing problem. The adapters that are fitted to the augers, thus, tend to clog with toner. The flow rates through such adapters is unacceptably low.
In accordance with the present invention, there is provided an apparatus for moving powder from a hopper containing a supply of powder to fill a container. The apparatus includes (a) a conduit member operably connected to the hopper and having a discharging end for permitting a powder to be moved therethrough; (b) a nozzle member for directing the powder from the conveyor to fill the container, the nozzle member being operably connected to the discharge end of the conduit member and having a first end connected to the conduit member, and a second and opposite end for dispensing moving powder into the container; and (c) a conveyor device located at least partially within the conduit member for moving the powder from the hopper in a powder moving direction to the nozzle member, the conveyor device being stoppable for halting the flow of powder, and including a porous portion and vacuum device for additionally halting the flow of powder for a clean shutoff.